Inertial navigation systems (INS) are used in civil and military aviation, missiles and other projectiles, submarines and space technology as well as a number of other vehicles. An INS measures the position and attitude of a vehicle by measuring the accelerations and rotations applied to the system's inertial frame. INSs are widely used because it refers to no real-world item beyond itself. It is therefore resistant to jamming and deception.
An INS may consist of an inertial navigation system combined with control mechanisms, allowing the path of a vehicle to be controlled according to the position determined by the inertial navigation system. A typical INS uses a combination of accelerometers and any number of control devices.
Inertial navigation systems have typically used either gyrostabilized platforms or ‘strapdown’ systems. The gyrostabilized system allows a vehicle's roll, pitch and yaw angles to be measured directly at the bearings of gimbals. The big disadvantage of this scheme is that it employs multiple expensive precision mechanical parts. It also has moving parts that can wear out or jam, and is vulnerable to gimbal lock. In addition, for each degree of freedom another gimbal is required thus increasing the size and complexity of the INS. Strapdown systems work well in some applications. One key difference is the ability of a rotating sensor assembly in a gyrostablized system to self calibrate periodically and thus maintain higher accuracy over a longer period of time.
Another type of inertial navigation system is one that floats a sensor assembly with neutral buoyancy in a fluid. This method requires an extremely complex assembly, sensitive temperature control and obvious sealing challenges that add considerably to the cost of deployment and maintenance. Also, many of these fluids are hazardous or require a high degree of purity.
For high accuracy applications, INSs mounted within vehicles require regular calibration. As a result there is a need for easy access to sensor and control mechanisms for adjustment.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a guidance system which is inexpensive and easy to access for adjustment mostly in the initial build phase and for rebalancing a system during a scheduled maintenance.